Joint between precast concrete slabs



lMarch 30, 1954 M, w. ovERHULsE JOINT BETWEEN PREcAsT CONCRETE sLABs Filed Feb. 25. 1950 INVENTOR. Mar/'0n VI/ Uve/*hU/Se aus Patented Mar. 3Q, 1954 UNITED STATES PTENT OFFICE J 01N T BETWEEN PRECAST CONCRETE SLABS 1 Claim.

This invention relates to the construction of tanks and particularly to the construction of underground tanks, such as septic tanks, from prefabricated concrete slabs.

While many underground tanks have been built from prefabricated units of various kinds, all of those of which I have knowledge have been subject to various disadvantages including, by way of example, diiliculty of installation and difficulty of maintenance and repair. For example, prefabricated units have been difficult to handle and have required skilled labor during construction. Furthermore, the junctions or joints between the various prefabricated parts have provided weak points Where breakage or leakage is apt to occur. The effect of the weakening of such underground units will, of course, be obvious. Seepage causes settling and washing away of the supporting earth. Lack of support for the walls of the tank then occurs at a point, which, having already been weakened, is not in condition to continue to carry the strain.

It is an object of the present invention to provide a simple type of prefabricated concrete slab from which tanks of various lengths and widths may be built by the use of the same basic slab.

It is a further object of this invention to provide means whereby the slabs may be joined together in such a manner that the entire completed structure forms, in effect, a single cast member.

It is a further object of this invention to provide means whereby the slabs may be joined to' gether in such a manner that the defects heretofore described will not be inherent in the device.

Other objects and advantages of the present invention will appear from the following speciflcation taken in conjunction with the accompanying drawings in which-- Figure 1 is a cross-sectional view of a septic tank manufactured from my concrete slabs;

Figure 2 is a perspective view, partly cut away,

of a septic tank manufactured from my concrete slabs;

Figure 3 is a three-quarter View of a concrete slab, partly cut away, incorporating my invention;

Figure 4 is detail taken along the line 'II- 4 of Figure l;

Figure 5 is a detail taken along the line 5-5 of Figure l and Figure 6 is a detail taken along the line 6-6 of Figure l.

As illustrated in Figure 1, conventional under- Jil) ground septic tanks consist of side and end walls IIJ and II, a, floor I2, a top I3 and a plurality of baffles I4 which are suitably secured to the side walls lll or the floor I2.

As illustrated in Figure 3, my preformed concrete slab I6 is provided with a central reinforcing web Il which, as illustrated in Figure 3, is preferably formed of expanded metal or wire mesh. The reinforcing web I 'I extends the entire length and width of the slab I6 and projects from the lower end I 8 of the slab I6 forming a strip I9 of expanded metal or wire mesh, whose purpose will more fully hereinafter be explained.

Adjacent the side edges of the slab IB, I also provide a pair of identical strips 2| of expanded metal or other reinforcing material. The strips 2i extend substantially the entire length of the member I6 and extend perpendicularly from the surface of the slab I6, as shown. Adjacent each of the strips 2| of reinforcing material I have provided a row of clips 22 which are likewise embedded in the reinforced concrete member I6. The clips 22 are spaced from each other and are preferably made of some readily deformable metallic material such as copper, etc.

The top and bottom edges of the slab I6 are straight except, however, for the strip I9 extending from the bottom edge I8 of the slab. The side edges of the slab I6, however, are tenon and mortise type. The tenons 26 are of the same length as the adjoining mortises 21 whereby, as illustrated, for example, in Figure 2, when a number of the members IB are joined, the tenons 26 and mortises 2l cooperate to provide a substantially tight junction. In addition, the upper shoulders 28 of the tenons 26 are substantially square. For this reason when a pair of members I6 is joined to form a corner, the tenons and mortises cooperate substantially as illustrated in Figures 2 and 4, whereby the faces 29 of the tenons 25 are flush with the adjacent outside surfaces of the slabs IS.

A septic tank, as illustrated in Figures 1 and 2, may be constructed from the precast units I6 in generally the following manner: A suitable excavation is made. A sufficient number of slabs I5 are provided and are joined along their vertical side edges in such a manner that the tenons and mortises 26 and 2l cooperate to support the slabs I6 and form side and end walls I0 and II. The extending sections I9 of expanded metal extend downwardly. The floor I2 may then be poured. It is obvious that when the floor I2 is poured, the wet mix will engage the sections I9 and form a bond therewith, In addition, a slight flnishing bevel 30 may be provided to strengthen the corner joint between the walls I0 and Il on the one hand and the floor I2 on the other. The upper surface of the base I2 may be troweled to form a substantially smooth and flat surface.

The baffles are also precast. However, they are rectangular in shape and are formed of concrete reinforced with a central web of expanded metal. Bafes I4 are slightly shorter in length than the inside width of the completed tank and are shorter in height than the inside height of the completed tank. The baffles I4 are then positioned within the walls I0 and II and the floor or base I2. The baffle I4a, it will be noted, extends upwardly from the base I2 and is secured thereto by the bevels 3D adjacent its base. The baiiles Illb and I4c are substantially identical and are adapted to be mounted in the tank in the following manner: It will be noted that the baffles |417 and I4c extend downwardly v from the roof I3 but do not reach the floor I2. A pair of wooden strips 3l are spaced a short distance outwardly from the wall I0 and extend upwardly from the base I2. Strips 3| are provided with a number of deformable clips 32 substantially identical to the clips 22 provided on the slabs IS. The vertical strips 2l of expanded metal are bent inwardly substantially as shown, for example, in Figures 5 and 6. A strip of plywood or any other` suitable material 33 is positioned generally as shown in Figures 5 and 6 and the clips 22 and 32 are deformed, as shown, to retain the same generally in the position illustrated. The baffles I4b and Ic are positioned with their lower edges I4d resting upon the upper ends of the strips SI. The baffles lIlb and I4c are provided with reinforcing webs generally as illustrated and are also provided with outwardly extending strips 34 formed of reinforcing material and with a plurality of clips 3G. The form material 33 extends upwardly and its upper end is retained in position by the clips 22 and 36. Cement is then poured into the space between the forms 33 and the walls I0. As the cement sets, the joint between the adjacent blocks I6 and the baiiles I4b and I4c sets and hardens. In this manner the bafiles I4b and I4c are positioned. The members 33 and 3l may be removed if it is found desirable although their being allowed to remain has no harmful effects.

A corner joint between the walls Il! and II is formed generally as illustrated in Figure 4. The strips 2| are bent in substantially as shown and a piece of plywood or other suitable form material 33 is positioned generally as shown and retained in place by the clips 22. Cement is then poured into the corner behind the form 33 which, after the cement has hardened, may or may not be removed, depending upon the wishes of the individual constructing the tank.

Suitable inlet and outlet pipes 31 and 38 may be provided. The top I3 may be provided with a number of manholes 39 which are provided with suitable covers 4I.

From the foregoing it will be obvious that I have invented a type of concrete slab construction which is particularly adaptable for use in connection with underground septic or storage tanks, for example.

It should be noted that by virtue of the tenon and mortise construction, substantial strength is originally provided. However, by virtue of the strips of reinforcing material 2|, which are cast integrally with the blocks I6, further reinforcing means are provided when additional wet con.. crete is poured either to form a joint as illustrated in Figures 5 and 6 or a corner as illustrated in Figure 4. It is also obvious that the size of the tank to be formed may be readily altered to suit particular conditions. For example, by the use of varying numbers of blocks in the formation of the walls, the tank may be lengthened 0r shortened. My precast slabs I6, therefore, provide the readily useable means for forming walls of varying lengths. In this manner and by the use of the same materials an almost unlimited adaptability is obtained. The use of blocks I6 together with the baffle members I4, together with a quantity of Wet mixed cement is all that is needed for the production of a suitable tank. The tank may thus be formed speedily and with the minimum of skilled labor. In addition, the advantages of water-tight junctions and corners is obtained. Furthermore, the additional concrete which is poured on the job to form a leakproof joint or corner in addition forms a support or anchorage for the baiiles.

I claim:

A structural joint comprising: a pair of reenforced concrete slabs securely positioned upon a concrete bottom member and having adjacent edges extending along said joint and a third reenforced concrete slab positioned at right angles to said pair of slabs and in the vertical plane of said joint and spaced from said bottom member, the edges of said pair of slabs having complementary interengaging notches and projections locking said edges against relative movement longitudinally of said joint, a row of spaced retaining clips embedded in each of said pair of slabs adjacent and parallel to said joint and projecting from corresponding faces of said slabs, a row of spaced retaining clips embedded in opposite faces of said third reenforced concrete slab adjacent to said joint and projecting from each face of said slab, means for spacing said third reenforced concrete slab from said bottom member comprising a structural member of approximately the same width as said slab and provided with spaced retaining clips embedded in opposite sides thereof and projecting from op posite faces thereof, a pair of form members,

each of said form members extending along but spaced from said joint and having one of its edges abutting one of said pair of slabs and the other of its edges abutting the said third. slab and said structural member, said retaining clips engaging the side edges of said form members to hold said members in position to define an enclosed space extending along said joint, separate reenforcing elements having portions embedded in each of said slabs respectively and terminal portions extending into said enclosed space, said enclosed space being lled with hardened bonding material.

MARION W. OVERHULSE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,384,003 Thompson July 5, 1921 1,551,430 Reynolds Aug. 25, 1925 1,557,523 Hahn Oct. 13, 1925 1,709,95 Saltiel Apr. 23, 1929 

